# RD4 - Groovebox > Mobile music production app with virtual synths, drum machines, and effects. (iPhone/iPad app by Nils Krüger und Toine Diepstraten.) - Source: https://appshunter.io/ios/app/rd4-groovebox/id675680226 (this page in markdown: same URL + `.md`) - Developer: [Nils Krüger und Toine Diepstraten](https://appshunter.io/developer/572564548) - Category: Music, Music - Price: Free with in-app purchases - Rating: 3.55/5 from 11 App Store ratings · 19 written reviews indexed - Age rating: 4+ - Requires: iOS 8.0 · 23 MB - Languages: English - Released: 2013-09-16 - Data updated: 2026-06-10 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/rd4-groovebox/id675680226/reviews.md ## What is RD4? Turn your iPhone or iPad into a musical instrument! RD4 - Groovebox is a music making app with virtual analog synthesizers, drum machines and effects. Compose and arrange your music in real-time. Choose instruments individually for the 4 channels. Record live or set notes with the dedicated sequencer or piano roll of each instrument. "This is no desktop app crammed onto a touchscreen. It seems the interface has been designed around your fingertips." Peter Kirn from CDM (createdigitalmusic.com) Via in-app purchase: Upgrade to premium and unlock the following features: Save Song, Export Loop, Audio Session Recording, Share Sounds, All 10 Drum Kits, All 5 Effects, Mixer Instrument Configuration, Effect Bus Configuration, MIDI Input and MIDI Clock Sync in/out. This multi-touch enabled app makes it simple to invent unique loops and musical phrases. Manipulate the sound of the synthesizers by tweaking the oscillators, resonant filters and audio envelopes. Add audio effects like reverb, distortion, phaser, filter and delay to your sounds. Appropriate both for experienced musicians and beginners. Feature Overview Mixer - 4 channel rack mixer - Instrument selection for each channel - Volume control with level meter per channel - Direct audio effect channel assignment - Tempo control with tap tempo - Channel mute and solo Sequencer - 2 banks with up two 8 bars per instrument - Adjustable play modes from 1 to 8 bars and random modes - Song Mode with a length of up to 99 bars Choose between two virtual analog synthesizers and the drum machine for each channel: Analog - Modeled after legendary monophonic synths of the '70s - For fat sounding bass and powerful lead sounds - 3 oscillators with 6 different waveforms - Each oscillator can be tuned precisely and has a warmth control for the typical analog sound - Attack, Decay, Sustain and Release envelope generator - Pitch wheel - Low-pass filter (24dB/oct, 4-pole) with knobs for cutoff, resonance and an Attack/Decay/Sustain envelope generator - Recording of played notes in real-time - Piano Roll for editing recorded notes comfortably - Or compose by drawing notes directly with the piano roll in 1/16 or 1/32 resolution - Piano roll editing features: Transpose Pattern, Shift Sequence and Quantize Pattern Bassline - Reminiscent of the legendary 303 synthesizer - Create bubbling basslines and screaming lead sounds - Successor of the famous synthesizer Rubberduck from d-lusion - High-quality low-pass filter with resonance, cut-off, and envelope controls - Oscillator with 4 types of waveforms - Real-time step sequencer with accent and slide Beats - Program beats with 10 classic drum kits: 808, 909, 606, CR-78, Linn, KR55, RX11, RZ1, DMX, DPM48 - Booming kick drums, snappy snares and throbbing percussions - 8 channels per drum kit - Punch control for volume and envelope adjustments - Accent programmable for each drum channel - Free assignable effects for each drum sound - Channel mute, Closed Hi Hat mutes the Open Hi Hat - Real-time pattern based step sequencer Audio effects: - 5 effects: Reverb, distortion, filter, phaser and delay - Real-time controllable - X/Y control field for each effect - 4 effect sends - Chaining of 2 effects Technical features: - Audiobus support - Core MIDI support - Connects to all available MIDI input sources automatically - MIDI Clock Sync support, in/out - Automatic MIDI input focus when switching Instruments - Multi-touch control - Live session recording - Audio loop export feature - Session save capability - Cut/copy/paste pattern ## Key features - Virtual analog synthesizers - Drum machines - Real-time composition and arrangement - Sequencer and piano roll - Multiple audio effects - 4-channel mixer ## Pricing and in-app purchases Base price: Free. **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | RD4 - Groovebox Full Version | $3.99 | one-time | ## Recent user reviews (10 of 19) All indexed reviews: https://appshunter.io/ios/app/rd4-groovebox/id675680226/reviews.md ### 1/5 — Crap *2022-11-04, version 2.3.8* Doesn’t work. The “Analog” is the only part that plays. The rest is nothing. ### 4/5 — It’s Fantastic! Also needs upgrades! *2021-04-28, version 2.3.8* The app is really worth playing and making music with! The 808, 909, 303, reverb, distortion, delay, and filter really works! Add on UPDATE: can you add crashes to the drum machines like for the 909 and the other ones? Also the 303 is not really accurate to the real TB303, when I adjust the knobs for the 303 extreme high Churps we’re going and I didn’t like that. Yes the 303 has chirps, but the one in this app has lots. If so can you probably fix that? Thank you. :) ### 5/5 — Nice! *2019-05-03, version 2.3.8* UPDATE - still worth 5 stars to me. Great for acidic loops. Easy export to AudioShare. Still like it! I'm giving it 5 stars right away because I found it so intuitive and easy to get some interesting results from. Compared to other similar apps it just seemed to click for me. I bought the IAP pretty quickly after trying it out. There's plenty more to explore but I'm already sold. I think they did a good job with this so far. ### 5/5 — Ignore The Hate *2018-04-28, version 2.3.8* RD4 is magnificent: one of the best workflows I've ever encountered for iOS music making and just the right balance of choice x limitation. The IAP is a bargain and the fact that one can have multiple 303 (or other) instances running simultaneously is a thing of pure beauty. RD4 sounds amazing as well and we're lucky to have it. Easy 5 stars. ### 1/5 — Was good now it’s not *2018-03-23* Was a free app. Update is just to pay to get the features back you used to have? And now your drums and bass lines are out of sync? Update? No new look, no new features, just $$ to get back what you had. Just an out of sync, dated looking rip off of the mc303. REALLY? Your update is to take away features and charge me to use them again. Just leave it as it was and make a newer version with a few more features and an updated design. I would have bought it. Greedy guys. Really. Make a new app and sell that. Don’t just disable functions and put them behind an iap. And on top of that, everything’s out of time now. Unusable. ### 1/5 — Longest "Bait and Switch" Scheme Ever Run In App Store *2018-03-13, version 2.3.8* Run from this app. The slim version is no longer worth the few seconds it takes to download. I've loved this app and have been using it regularly for a very long time—previously had my review at four stars—until this afternoon, when an automatic update removed all but one of its drum kits and many of its other features. Tapping restore does nothing to restore any of the elements I've been using without a problem for the entire time I've been using the app. I'm not sure why the developers felt it necessary to utterly neuter, and thus eliminate the possibility of enjoying, the user experience, but for anyone in the market for an app that's a versatile groovebox, drum machine, synth, etc., and you've heard good things about this one, ignore what you've heard. More important, though, can you really trust developers who decide without warning to take away features you've had and have been using for years in order to engage in a scheme to begin charging for them? In my view, absolutely not. ### 5/5 — Brilliant and free *2017-07-09* I use this in in Audiobus 2 with a number of other rhythm apps and this syncs well with everything via Ableton Link. The functionality is brilliant for a free app. Programming it is easy and the range of options for stacking rhythms is spot on. A great free tool. Thanks. ### 1/5 — Great just needs.... *2017-02-08* What's happened to this app ? Can't keep tempo now. Glitches galore !?? ### 2/5 — Link crashes app *2016-12-05, version 2.3.4* Tapping Link crashes the app. In-app keys respond slow. Sequence fidgets while actively controlling things. 303 sounds aight I guess. Nice that they give a little bit fix. ### 1/5 — Feedback *2016-06-24* Sorry, wish it was better not so great interface, samples sound old 8bit cheesy. Waste of time! ## Frequently asked questions about RD4 ### What instruments are available in RD4 - Groovebox? RD4 - Groovebox features two virtual analog synthesizers and a drum machine for each of its four channels. The synthesizers are modeled after classic monophonic synths and a 303-style synth, while the drum machine offers 10 classic drum kits. ### Can I save and export my music from RD4 - Groovebox? Saving songs, exporting loops, and audio session recording are available as premium features unlocked via in-app purchase. This allows for more comprehensive project management and sharing of your creations. ### Does RD4 - Groovebox have ads? No, RD4 - Groovebox does not contain advertisements. The app is free to download and use, with optional in-app purchases for advanced features. ### What devices is RD4 - Groovebox compatible with? RD4 - Groovebox is designed for iOS devices, specifically compatible with iPhone, iPad, and iPod. It leverages multi-touch capabilities for an intuitive user experience. ### How often is RD4 - Groovebox updated? The app was last updated on March 13, 2018, to version 2.3.8. While updates have not been frequent recently, the existing features provide a robust music-making experience. ### What are the premium features in RD4 - Groovebox? The premium upgrade unlocks features such as saving songs, exporting loops, audio session recording, sharing sounds, all drum kits and effects, advanced mixer configurations, and MIDI input/output synchronization. ### Is RD4 - Groovebox suitable for beginners? Yes, RD4 - Groovebox is appropriate for both experienced musicians and beginners. Its interface is designed to be intuitive, making it easy to invent unique loops and musical phrases. ### What is the user rating for RD4 - Groovebox? RD4 - Groovebox has a user rating of 3.5 stars based on 11 ratings. This indicates a generally positive reception, though with some room for improvement noted by users. ## Version history (last 5 releases) ### 2.3.8 — 2018-03-13 This app has been updated by Apple to display the Apple Watch app icon. - broken in-app purchase fixed ### 2.3.7 — 2018-02-23 bugfix update ### 2.3.6 — 2017-05-16 - fix sequencer hiccups - fix iPad share sound crash ### 2.3.5 — 2017-02-07 - added new drum kit and demo song - fixed crash on iPad with Ableton Link Settings - fixed main screen bounds bug after pressing the device’s power button ### 2.3.4 — 2016-12-05 New version 2.3.4 now with Ableton Link integration. ## Apps similar to RD4 | App | Rating | Price | Category | | --- | --- | --- | --- | | [Synthcussion2022](https://appshunter.io/ios/app/synthcussion2022/id1614811916) | 4.3 (8) | Free | Music | | [Mr Beat](https://appshunter.io/ios/app/mr-beat/id1540943168) | — | Free | Music | | [Factory - Modular Synthesizer](https://appshunter.io/ios/app/factory-modular-synthesizer/id1458743434) | 4.9 (477) | Free | Music | | [4Waves Synth AUv3](https://appshunter.io/ios/app/4waves-synth-auv3/id1545450649) | 4.6 (5) | Free | Music | ## More apps by Nils Krüger und Toine Diepstraten - [RoboVox - Voice Changer](https://appshunter.io/ios/app/robovox-voice-changer/id584847250) All apps by Nils Krüger und Toine Diepstraten: https://appshunter.io/developer/572564548 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*